Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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G-CSF receptor targeting in inflammatory arthritis

ABSTRACT: G-CSF is a hemopoietic growth factor that has a role in steady state granulopoiesis, as well as in mature neutrophil activation and function. We developed a neutralizing monoclonal antibody to the murine G-CSF receptor (G-CSFR), which antagonizes binding of murine G-CSF and inhibits G-CSFR signalling. Anti-G-CSFR rapidly halts the progression of established disease in collagen antibody-induced arthritis (CAbIA). Neutrophil accumulation in joints is inhibited, without rendering animals neutropenic, suggesting an effect on homing to inflammatory sites. Neutrophils in the blood and arthritic joints of anti-G-CSFR treated mice show alterations in cell adhesion receptors, while anti-G-CSFR suppresses local production of proinflammatory cytokines and chemokines known to drive tissue damage. Our aim in this study was to use differential gene expression analysis of joint and blood neutrophils to more thoroughly understand the effect of G-CSFR blockade on the inflammatory response following anti-G-CSFR therapy in CAbIA. C57BL/6 mice with collagen antibody-induced arthritis were injected intra-peritoneally at day 5 with 50 Î¼g anti-G-CSFR (n = 20 mice) or control mAb (n = 10 mice). At day 7, neutrophils (CD45+ CD11bhi Ly6G+) were sorted (BD FACSAria) from pooled digests of the knee tissues, or peripheral blood, and the RNA was extracted from 3 such experiments, giving a total of 12 samples.

ORGANISM(S): Mus musculus

SUBMITTER: Ian Campbell

PROVIDER: E-GEOD-76966 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:[Background] TNFa-induced adipose-related protein (TIARP) is a six-transmembrane protein that is expressed on macrophages, neutrophils and synoviocytes. We have recently reported that TIARP deficient mice (TIARP-/-) spontaneously developed arthritis, and had the high susceptibility to collagen-induced arthritis (CIA) with enhanced interleukin (IL)-6 production. However, the effect of TIARP to neutrophils and fibroblast-like syonoviocytes (FLS) has not been clearly elucidated. [Methods] We analyzed the roles of TIARP in K/BxN serum transfer model using TIARP-/- mice. We characterized the differences of neutrophils between WT and TIARP-/- mice by DNA microarray. Transmigration assays of TIARP-/- neutrophils were performed in vitro and in vivo. FLS were cultured with TNF? and the production of CXCL2 (a specific ligand of CXCR1 and CXCR2) and IL-6 were measured by ELISA. Moreover, TIARP-/- mice transferred with K/BxN serum were treated with anti-IL-6R antibodies. [Results] Arthritis in TIARP-/- mice transferred with K/BxN serum was significantly exacerbated. We identified overexpression of CXCR1 and CXCR2 in TIARP-/- neutrophils by DNA microarray. Neutrophils from TIARP-/- mice showed strong migration activity. The enhancement of chomotactic activity of TIARP-/- neutrophil was greatly facilitated by CXCL2 in vitro and in vivo. In addition, TIARP-/-FLS has enhanced the production of CXCL2 and IL-6 and the cell proliferation in the presence of TNFa, and the blockade of IL-6R significantly attenuated arthritis in vivo. [Conclusion] Our findings indicate that TIARP might down-regulate the production of CXCL2 and IL-6 in FLS, and the expression of chemokine receptors (CXCR1 and CXCR2) in neutrophils, resulting in the protective ability of neutrophils migration into arthritic joints. Mice were treated with thiogycollate medium intraperitoneally. After 3 days, peritoneal macrophages were isolated from three WT or TIARP-deficient mice, and these cells were stimulated by TNF? for 24 hours. Ly6G+ Neutrophils were isolated from splenocytes by MACS.

Project description:Rheumatoid arthritis is an inflammatory disease of the synovial joints that affects ~1% of the human population, with severe distress due to progressive joint inflammation and deformation. When addressing the links between specific components of the apoptotic cell clearance machinery and human disease, we noted a correlation between single nucleotide polymorphisms (SNPs) in ELMO1, DOCK2, and RAC1 genes and rheumatoid arthritis. ELMO1 is a cytoplasmic adapter protein that associates with DOCK2 and RAC1 to promote cytoskeletal reorganization needed for apoptotic cell uptake by phagocytes. We initially hypothesized that, since ELMO1 is linked to apoptotic cell clearance, loss of ELMO1 would lead to increased inflammation in arthritis. Contrary to the accumulation of apoptotic cells and greater disease severity that we predicted, we observed significantly reduced joint inflammation in two models of arthritis in mice lacking ELMO1. Using genetic and cell biological approaches in vivo and ex vivo, we determined that ELMO1 deficiency significantly reduces neutrophil recruitment to inflamed joints, but does not result in general inhibition of inflammatory responses. Through proteomic analyses, we find that ELMO1 protein associates with cellular receptors that contribute to neutrophil function in arthritis, and regulates C5a and LTB4 receptor-mediated activation and early neutrophil recruitment to the joints. Neutrophil-specific transcriptomics show that ELMO1 modulates neutrophil-specific gene expression that includes genes with known linkages to human arthritis. Finally, neutrophils from the peripheral blood of human donors that carry the SNP in ELMO1 associated with arthritis display increased migratory capacity, whereas ELMO1 knockdown reduces human neutrophil migration to LTB4. These data identify key ‘non-canonical’ roles for engulfment machinery components in arthritis, and ELMO1 as an important regulator of specific neutrophil receptors and signaling linked to arthritis.

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G-CSF receptor targeting in inflammatory arthritis

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